geom3d

Calling Sequence

[x,y]=geom3d(x1,y1,z1)

Arguments

x1,y1,z1

real vectors of the same size (points in 3D).

x,y

real vectors of the same size as x1,
y1 and z1.

Description

After having used a 3D plot function such as plot3d,
plot3d1 or param3d, geom3d gives
the mapping between a point in 3D space (x1(i),y1(i),z1(i))
and the corresponding point (x(i),y(i)) in the projected 2D
plan. Then all the 2D graphics primitives working on (x,y)
can be used for superposition on the 3D plot.

Examples

deff("[z]=surface(x,y)","z=sin(x)*cos(y)")t=%pi*(-10:10)/10;// 3D plot of the surfacefplot3d(t,t,surface,35,45,"X@Y@Z")// now (t,t,sin(t).*cos(t)) is a curve on the surface// which can be drawn using geom3d and xpoly[x,y]=geom3d(%pi/2,0,surface(%pi/2,0))

my_plot_desc="plot3d and use of geom3d";r=(%pi):-0.01:0;x=r.*cos(10*r);y=r.*sin(10*r);deff("[z]=Surf(x,y)","z=sin(x)*cos(y)");t=%pi*(-10:10)/10;// Plot the surface'fplot3d(t,t,Surf,35,45,"X@Y@Z",[19,2,3]);// Add 2d graphics on 3d graphic'z=(sin(x).*cos(y));[x1,y1]=geom3d(x,y,z);xpoly(x1,y1,"lines");// Adjust some plotting parameters'BackgroundColorId=color(70,174,255);current_axe=gca();plot_3d=current_axe.children(2);plot_3d.hiddencolor=32;polyline=current_axe.children(1)';;polyline.foreground=8;current_axe.rotation_angles=[70,47];current_axe.background=BackgroundColorId;// A second 2d graphics'[x1,y1]=geom3d([0,0],[0,0],[5,0]);xsegs(x1,y1);xstring(x1(1),y1(1),"The point (0,0,0)");xtitle(my_plot_desc,"","","");